The short answer:
‍HIIT and endurance training both support health and fitness, but they work in different ways. New research suggests vigorous exercise may deliver greater health benefits per minute, while endurance training remains valuable for aerobic fitness, consistency, and recovery. For most people, the strongest approach is combining regular endurance work with one or two high-intensity sessions each week.

Key takeaways

‍
• Vigorous exercise appears to offer strong health benefits, even in relatively small doses.
• HIIT can be a time-efficient way to improve cardiovascular fitness, metabolic health, and body composition.
• Endurance training remains valuable for aerobic fitness, consistency, recovery, and frequent movement.
• For most people, a balanced routine can include regular endurance work and one or two high-intensity sessions each week.
• Recovery matters, especially when adding higher-intensity training.

‍

For years, the fitness world has bounced between two extremes.

First, there was the belief that long, steady cardio was the gold standard. Then high-intensity interval training (HIIT) burst onto the scene, bringing promises of bigger results in less time. Suddenly, it seemed every workout needed to leave you gasping for air.

Now, a major new 2026 study has highlighted that high-intensity exercise really is a winning way to move. But before you abandon your long runs, rides, and endurance classes, the full story is a little more nuanced.
The latest evidence suggests that vigorous exercise can offer notable health benefits. Yet endurance training continues to provide unique advantages that intense intervals alone may not fully replicate. Bryce Hastings, Les Mills Head of Research, says the smartest approach is less about choosing sides and more about understanding when and how to use both.

Does exercise intensity matter more than time?

A 2026 study published in the European Heart Journal examined physical activity data from nearly half a million people and explored the relationship between exercise habits and the risk of eight major chronic diseases. Researchers found that the proportion of vigorous physical activity in a person's routine was more strongly associated with lower disease risk than the total amount of activity performed.

In other words, how hard you exercise may matter as much as, and in some cases more than, how long you exercise.

Participants who accumulated more than 4% of their activity at vigorous intensity experienced substantially lower risks of the following: major cardiovascular events, type 2 diabetes, dementia, chronic respiratory disease, chronic kidney disease, liver disease, atrial fibrillation, and immune-mediated inflammatory diseases.

They also had a significantly lower risk of dying from any cause. These associations remained even after researchers accounted for differences in overall physical activity volume.

For anyone who regularly uses ‘lack of time’ as a reason to skip exercise, this could be good news. The findings suggest that increasing intensity may improve the health return from limited exercise time.

Why does exercise intensity matter?

We already knew vigorous exercise was effective. What stands out is how strongly it appears to be associated with better health outcomes.

Across every condition studied, exercise intensity demonstrated greater preventive potential than exercise volume. For some conditions, including dementia and immune-related inflammatory diseases, intensity appeared to contribute substantially more than total exercise volume.

The researchers also found that benefits began appearing at relatively modest amounts of vigorous activity. So, you don’t need to train intensively like an elite athlete, but if you incorporate brief periods of challenging effort into your week, it can have meaningful health benefits.

An earlier study, involving wearable data from more than 73,000 adults, supports this. Assessing outcomes related to all-cause mortality and cardio metabolic health, researchers found each minute of vigorous-intensity activity delivered the same benefit as four to nine minutes of moderate exercise, or more than 50 minutes of light activity. In other words, vigorous exercise was at least four times more powerful than moderate exercise for protecting the heart.

This challenges the long-held assumption that one minute of vigorous exercise equals two minutes of moderate activity. It also invites closer consideration of current World Health Organization guidelines, which suggest 150–300 minutes of moderate activity delivers similar benefits to 75–150 minutes of vigorous activity. According to Hastings: “What we now know is that training at a higher intensity is far more potent than we once thought.”

What counts as vigorous exercise?

Vigorous exercise is activity that makes you breathe hard, raises your heart rate significantly, and makes speaking difficult. It typically sits around 70 to 85% of maximum heart rate. During HIIT, peak intervals may rise above 90% of maximum heart rate, which is why HIIT workouts are a surefire way to push your body into the vigorous intensity training zone.

What is HIIT?

HIIT stands for high-intensity interval training. It involves short bursts of hard effort followed by recovery periods. A HIIT workout is designed to push the body close to maximum effort for brief intervals, making it a time-efficient way to improve cardiovascular fitness.

What are the benefits of HIIT?

Research has shown HIIT can:

• Improve cardiovascular fitness and VO₂ max
• Increase lean body mass
• Reduce abdominal fat
• Improve metabolic health

Some studies have found that very small doses of HIIT can produce improvements comparable to much longer moderate-intensity sessions. A 2026 study from Newcastle University found that as little as 10 minutes of hard physical activity can release a surge of beneficial molecules into the bloodstream. These molecules are linked to reduced inflammation, healthier blood vessels, and improved metabolic function.
‍

For busy people, that makes HIIT a practical option to consider.

What are the advantages of HIIT?

• Highly time efficient
• Delivers rapid fitness improvements
• Builds cardiovascular capacity
• Improves metabolic health
• Supports body composition goals
• Many find it more enjoyable than traditional steady-state training

What are the limitations of HIIT?

HIIT is undoubtably a good thing, but there is a catch. A 2018 study highlights how you can't go all-out every day. Too much high-intensity training can increase fatigue, recovery demands, and the risk of overreaching.
HIIT is effective because it places significant stress on the body. That stress can support adaptation, but it also increases the need for recovery. (You can learn more about the best HIIT prescription).

Who should be cautious with HIIT?

• Those who are training without a recovery day
• Beginners without a fitness base
• People returning from injury
• Anyone already struggling with recovery or fatigue

As effective as HIIT is, it's difficult to build an entire exercise lifestyle around maximum effort. This is where endurance training comes in.
Endurance training has something powerful on its side: decades of evidence. Dr. Jinger Gottschall, Adjunct Associate Professor, Columbia University, says: "We have decades of research demonstrating the effectiveness of longer duration workouts. The existence of exciting new interval training research doesn't suddenly erase the value of steady-state training to build endurance.”

What are the benefits of endurance training?

Endurance training may not always attract the same attention as newer training trends, but it remains one of the most established tools in fitness.

This is becoming increasingly relevant as endurance-focused communities and events gain momentum. Run clubs continue to draw people into regular aerobic training, while fitness races such as HYROX show how endurance and functional strength often work together. With 1.3 million people expected to race in a HYROX event over the next 12 months, and each race combining 8km of running with eight functional training stations, cardiovascular endurance remains a clear advantage.

Longer-duration, moderate-intensity exercise allows you to build aerobic fitness, improve cardiovascular health, and accumulate meaningful training volume without excessive fatigue.

Canadian researchers compared sprint interval workouts to endurance sessions over a period of six weeks. Twenty-three overweight/obese males were randomly assigned to one of two groups. The sprint group did four to six intervals of 30 seconds duration, at maximum intensity on a stationary bike, with two minutes of recovery between each set. They performed this exercise session three times per week. The endurance group did five biking sessions per week of 30 – 40 mins duration, each at 60 percent of their maximum intensity.

Both groups improved fitness and glucose tolerance. However, the endurance group saw additional benefits, including reductions in blood pressure, abdominal fat, and post-meal blood-fat accumulation
Endurance training also supports one of the most underrated elements of health and fitness: consistency. Because it is generally easier to recover from, you can perform it more often and make it a regular part of your lifestyle.

What are the advantages of endurance training?

• Sustainable and accessible
• Lower recovery demands
• Supports cardiovascular health
• Helps reduce blood pressure
• Builds aerobic capacity and stamina
• Makes frequent exercise possible
• Supports long-term adherence

What are the limitations of endurance training?

• Requires more time
• Fitness gains may arrive more gradually
• Less efficient than vigorous exercise when time is limited
• May not produce the same degree of intensity-driven health benefits seen with HIIT

Should you combine HIIT and endurance training?

Perhaps the most valuable lesson from the research is that this isn't really a competition.

Sprint intervals are great. Endurance sessions are great too. The evidence increasingly suggests that combining both may deliver broader overall benefits.

A study published in the Open Journal of Preventative Medicine, found that active adults who combined moderate-to-vigorous training with two weekly high-intensity sessions improved cardiovascular fitness, strength, triglyceride levels, and other health markers in just six weeks. Participants also reported high levels of enjoyment and satisfaction with the variety of training.

There is another factor to consider: frequency.

Training most days, whether it's high-intensity or endurance, means you are moving more often and offsetting the effects of being sedentary.

Endurance training makes frequent movement easier, while HIIT provides a strong physiological stimulus that can drive adaptation.

Together, they can create a useful training partnership.

How should everyday exercisers balance intensity and endurance?

You do not need to turn every workout into an all-out blitz.

A practical approach could look like this:

• Move most days of the week
• Build a foundation of regular aerobic exercise
• Include one or two vigorous sessions weekly
• Mix different training styles
• Allow time for recovery
• Focus on consistency rather than perfection

If your exercise of choice is a daily walk, you might add short uphill intervals. If you’re a runner, you might schedule one weekly speed session. And if you love the energy of group workouts, you can combine endurance-based classes with occasional HIIT workouts.

The goal isn't replacing endurance training. It's complementing it.

Is there a hybrid of high intensity and endurance training?

Yes, this is where Cardio Peak Training comes in. A Cardio Peak Training workout is where you maintain your heart rate at an aerobic training base, between 60% and 80% of your maximum heart rate, and this is interspersed with peaks of intensity pushing you above 85% of your max. After a peak, you only drop back to your aerobic base.

Workouts like BODYATTACK™, BODYCOMBAT™, BODYSTEP™ and RPM™ are all great examples of Cardio Peak Training.

The advantages of Cardio Peak Training are highlighted in a Loughborough University study. Researchers analyzed the effectiveness of multi-peak cardio training by following a group of exercisers completing three Cardio Peak Training cycle workouts a week for eight weeks. They measured glucose tolerance, cholesterol, cardio fitness and body composition before and after the trial.

Cardio fitness improved after just eight weeks, with an 11.8% increase in VO2 max (the most common measure of cardio fitness) and a 7% reduction in (systolic) blood pressure. Body composition also improved considerably, with a 13.8% reduction in body fat and a 3% reduction in waist circumference. There was also a total cholesterol reduction of 13%. Perhaps even more significant was the 95% percent compliance rate among participants.

This suggests that anyone who enjoys the variety and challenge that comes from interval-based exercise will find Cardio Peak Training highly motivating. Unlike its challenging cousin HIIT, Cardio Peak Training gives you an intense cardio fix with less risk of overtraining. Cardio Peak Training is something you can safely do every day – although dedicating all of your training time to cardio exercise is not recommended. Learn why a mix of cardio and strength training is a winner and why you should also allow time for mobility/flexibility work and recovery.

What is the bottom line on HIIT vs endurance training?

The newest science points to a clear theme: intensity matters. Even relatively small amounts of vigorous exercise appear to be associated with meaningful reductions in chronic disease risk and premature mortality.

Endurance training remains valuable too. It helps build cardiovascular fitness, supports recovery, enables frequent movement, and delivers health benefits that are strongly supported by decades of research.  

For most exercisers, the practical takeaway is to use both intensity and endurance, rather than treating them as opposing choices.

The smartest advice: try to be active most days. Embrace training in sprint intervals a couple of times a week to give your fitness a nudge. And treat endurance training as equally valuable. After all, a burst of HIIT might help you outrun the proverbial grizzly bear, but it’s only endurance training that will help ensure you have the stamina to come back and do it again tomorrow.
‍

‍

Frequently asked questions

Is HIIT better than endurance training?

HIIT can deliver strong fitness and health benefits in less time, especially when it comes to vigorous-intensity training. Endurance training remains important for aerobic fitness, consistency, recovery, and frequent movement. For most people, a combined approach is likely to be more balanced.

Can HIIT replace endurance training?

HIIT can improve fitness efficiently, but it does not need to replace endurance training. Longer, moderate-intensity sessions support stamina, cardiovascular health, and sustainable exercise habits. A mixed routine can offer a more complete fitness base.

How often should you do HIIT?

One or two HIIT sessions a week can be a practical target for many regular exercisers. Because high-intensity training places greater stress on the body, it’s worth spacing sessions across the week and allowing enough recovery between them.

What counts as vigorous exercise?

Vigorous exercise is activity that raises your heart rate significantly, makes breathing feel challenging, and makes speaking difficult. It can include sprint intervals, fast cycling, steep uphill efforts, or high-intensity group training.

What is the best workout for longevity?

The evidence points to regular movement, a mix of intensities, and long-term consistency. Vigorous exercise may provide strong health benefits per minute, while endurance training helps make frequent exercise more sustainable. Strength training can also be an important part of a balanced routine.

‍